Many people (especially women) overtrain their abs, focusing on them every day of the week but they very rarely see the results which they hope for. Of course it is important to engage your core in every workout which you do, but is it necessary to train them in every session? The answer is simply NO. Without giving your abs the correct amount of time to recover, the results won't mirror your ha...rd work.
Many top athletes haven't performed a sit up in their life; abs is 80% nutrition, 20% training. To give your abdominal muscles enough recovery time in order to see results, only 2 sessions a week are required.
Try out these two very simple ab workouts, along with a very clean diet and you have guaranteed results: